The present invention relates to a hydraulic unit for a hydraulic controlling or regulating device for use as a braking pressure regulating device in anti-lock control systems or traction slip control systems for use on automotive vehicles. The hydraulic unit includes a valve-accommodating member accommodating at least one electromagnetically switchable valve and further including hydraulic components such as non-return valve, a throttle, etc.
German published patent application 2504972 discloses an electromagnet having a current-operated coil and a stationary, magnetizable core, and further including a non-magnetic guide tube for an armature movable under magnet force and a device for preventing the armature from becoming magnetically stuck on the stationary core. The armature is furnished with a flange outside of the guide tube in a known manner. The distance between the flange surface facing the guide tube and the end surface of the guide tube adjacent to the flange is smaller than the possible stroke of the armature in the direction of the stationary magnet core, the stroke being a predetermined distance.
Furthermore, another controlling or regulating system is known from German published patent application 3236535. This controlling or regulating system comprises at least one generator (control command generator and/or measured-value generator), an electronic evaluating circuit for the generator signals and at least one solenoid valve. The valve is driven by the electronic evaluating circuit and is inserted in a hydraulic or pneumatic actuating system. The evaluating circuit is arranged in the vicinity of the valve.
In this system the evaluating circuit and the electromagnet(s) of the solenoid valves are accommodated in one common housing and are interconnected. The valve parts of the at least one solenoid valve are incorporated in one separate block, and the common housing is attached to this block. At least one valve is actuatable by way of the at least one tappet which extends out of the common housing and which is displaceable by the electromagnet.
German patent application P 3729216 describes a hydraulic unit for a hydraulic controlling or regulating device, more particularly for a braking pressure regulating device in anti-lock control systems or traction slip control systems for automotive vehicles. At least one valve block is provided comprising a group of electromagnetically switchable valves, and a connector for further components of the controlling or regulating device.
The pressure fluid inlets and outlets of the electromagnetically switchable valves which are to be connected in terms of circuitry with pressure fluid inlets and outlets of the further components of the controlling or regulating device are placed in the area of an outside surface of the valve block. The pressure fluid inlets and outlet of the controlling or regulating device are arranged in the area of an outside surface of the connector of the controlling or regulating device. There is provision of at least one distributor element containing pressure fluid channels which inter-connect inlets and outlets of the valve block allocated in terms of circuitry, on the one hand, and inlets and outlets of the further components of the controlling or regulating device, on the other hand.
It is an object of the present invention that considerable weight reduction of the entire hydraulic unit is to be accomplished. The steel valve blocks used are to be significantly reduced. In steel valve blocks as they are described for instance in German patent application P 37 29 216.1 a diminuition of the blocks becomes possible to such extent that only so much material remains as is necessary for jamming the valve assemblies in the valve-accommodating member. The non-return valves incorporated in the valve block, for instance, are an obstacle when attempting a reduction or diminution of the valve blocks. It is one of the objects of this invention to eliminate this drawback. Further, standardization of all non-return valve bores is to be accomplished. For the non-return valve function itself, only very small space requirement should be necessary. The manufacture and assembly of the non-return valves is to be rendered less expensive.
Moreover, it is an object of the present invention to enable a simple inspection of single hydraulic components separately and from the outside. This applies especially for the inspection of the non-return valves. Such inspection is to be possible from the outside merely by observation. One of the objects of the present invention is to provided for permitting use of a new type of non-return valve which is simple and inexpensive, which is made of a sheet-metal part and which does not necessitate careful machining of the surfaces of those component parts which are essential for their functioning.
Furthermore, the invention provides that the areas of accommodation for the non-return valves can be machined from the outside and that the non-return valves themselves can be mounted on the valve block from the outside. This results in a considerable cost reduction of the manufacture and assembly of the hydraulic unit and renders the entire hydraulic unit more appropriate for automated and mechanical manufacture and assembly.